Conventionally, chloroprene rubber compositions for manufacturing hydraulic hose and high pressure hose in which a reinforcing layer having a surface plated with a metal such as brass is sandwiched by a pair of rubber layers have been proposed (e.g. see Japanese Unexamined Patent Application Publication No. 2001-279022A). Since this rubber composition contains a vulcanization accelerator such as sulfurs and guanidines, crosslinking characteristics of a rubber layer formed from the rubber composition is enhanced, and adhesion between a metal surface of the reinforcing layer and the rubber layer is enhanced.
Methods of manufacturing hose described above include a steam vulcanization method in which the rubber composition is heated and vulcanized by steam, and an oven vulcanization method in which the rubber composition is heated and vulcanized by an oven. Since the oven vulcanization method allows continuous vulcanization, productivity of hose can be enhanced.
However, when vulcanization of a rubber composition is performed by the oven vulcanization method, sufficient adhesion between the rubber layer and the reinforcing layer may not be always obtained due to vaporization of remarkable amount of water during the vulcanization. Therefore, there has been a demand for a rubber composition that has excellent heat resistance and that can provide a rubber layer having excellent adhesion toward a reinforcing layer even when vulcanized by a hot-air vulcanization method such as the oven vulcanization method.